Sensitivity of deformation demands in buildings to modeling assumptions in nonlinear seismic analysis

Abstract

Performance-based design principles rely heavily on the estimation of engineering demand parameters through nonlinear static or dynamic analysis. The increased focus on nonlinear analysis in recent and upcoming building codes calls for a detailed investigation into the lim- itations of these procedures. This is especially true for nonlinear dynamic analysis, which is often referred to as “exact” or “benchmark” solution. This article examines the sensitivity of nonlinear analysis results to the assumptions made in the modeling of nonlinear element be- havior. To this end, a four-story reinforced concrete building designed according to the recent European standards is modeled in OpenSEES computational environment. Nonlinear element behavior is modeled using several approaches from lumped plasticity models to force-based and displacement-based elements with fiber sections using complex stress-strain curves. The results of nonlinear static and dynamic analysis reveal that the modeling assumptions have a significant effect on both displacement demands at the story and global level. More specifically, the curvature demands at the bottom of the ground story columns are very significantly affected by the modeling assumptions, particularly for diplacement- and force-based elements.